A US company plans to send a fleet of spacecraft into the solar system to mine asteroids for metals and other materials in the hopes of furthering exploration of the final frontier.

"Using resources harvested in space is the only way to afford permanent space development," said David Gump, chief executive of Deep Space Industries, noting that more than 900 new asteroids that pass near our planet are discovered each year.

"In this case, metals and fuel from asteroids can expand the in-space industries of this century. That is our strategy."

In a first step, the company plans to send "asteroid-prospecting spacecraft" into the solar system, with the first -- 55-pound (25-kilogram) "FireFlies" -- to be launched in 2015 on journeys of two to six months.

These will be followed as of 2016 by heavier 70-pound "DragonFlies" that will go on two- to four-year missions and bring back samples.

"This is the first commercial campaign to explore the small asteroids that pass by Earth," said Deep Space Chairman Rick Tumlinson.

"Using low-cost technologies and combining the legacy of our space program with the innovation of today's young high tech geniuses, we will do things that would have been impossible just a few years ago."

If all goes according to plan, Deep Space Industries predicts that, in a decade, it will be harvesting metals and other building materials from space rocks to build large platforms to replace communications satellites -- followed by solar power stations that would beam carbon-free energy back to Earth.

"We will only be visitors in space until we learn how to live off the land there," Tumlinson said in a statement that also made a pitch for customers and sponsors.

"We are squarely focused on giving new generations an opportunity to change not only this world but all the worlds of tomorrow. Sounds like fun, doesn't it?"

Deep Space Industries is the second company to enter into the asteroid-mining business, following in the footsteps of Planetary Resources, which launched in April 2012 with the backing of top Google executives and film director James Cameron.